Susceptibility of common ragweed to the herbicides foramsulfuron, prosulfuron, thifensulfuron and imazamox

Ambrozija je najučestalija korovna vrsta okopavinskih usjeva kontinentalne Hrvatske. Uzrokuje značajne gubitke prinosa poljoprivrednih usjeva, a predstavlja i veliki javno-zdravstveni problem zbog peludi koja je jak alergen za ljude i životinje. U većini ratarskih usjeva ambrozija se suzbija herbicidima inhibitorima acetolaktat sintaze. Cilj ovog istraživanja bio je biotest metodom utvrditi osjetljivost ambrozije na herbicide foramsulfuron, prosulfuron, tifensulfuron i imazamoks. U plasteniku su uzgojene biljke ambrozije te su u razvojnoj fazi BBCH 12-14 tretirane linearno padajućim dozacijama istraživanih herbicida (2x – 1/64x; x= registrirana doza herbicida). Osjetljivost ambrozije utvđena je vizualnom ocjenom oštećenja, 7, 14, 21 i 28 dana nakon tretiranja (DNT) i redukcijom suhe nadzemne mase. Rezultati istraživanja pokazuju da su sva četiri istraživana herbicida učinkovita na ambroziju, ali i da je ambrozija različito osjetljiva na istraživane herbicide. Simptomi oštećenja nadzemne mase ambrozije progresivno su rasli od prve (7 DNT) do zadnje vizualne ocjene oštećenja (28 DNT) za sve istraživane herbicide. Najjača oštećenja nadzemne mase ambrozije utvrđena su kod herbicida foramsulfuron (94% - 28 DNT), a najmanja kod imazamoksa (78% - 28 DNT) pri registriranim dozacijama herbicida. Logisičkim krivuljama procijenjene su dozacije herbicida za 90%-tnu redukciju svježe nadzemne mase ambrozije (ED90): foramsulfuron = 10,11 ha-1 g; tifensulfuron = 5,34 g ha-1 imazamoks = 102,4 g ha-1. Dobiveni podaci ukazuju da je ambrozija pokazala različitu osjetljivost ovisno o aktivnoj tvari ALS herbicida pa su herbicidi rangirani prema procijenjenoj dozi potrebnoj da reducira 50 ili 90% nadzemne mase ambrozije (od boljeg prema lošijem): prosulfuron<foramsulfuron<tifensulfuron<imazamoks.Ambrosia is the most common weed species of root crops in continental Croatia. It is an extremely aggressive weed species and due to its characteristics it is considered invasive. It causes significant losses in crop yields and is a major public health problem due to pollen, which is a strong allergen for humans and animals. The purpose of this research was to confirm, by the bio-test method, susceptibility of ragweed to the herbicides foramsulfuron, prosulfuron, thifensulfuron and imazamox. Plants were grown in the greenhouse and in the development phase BBCH 12-14 were treated with linearly decreasing dosing of investigated herbicides (2x - 1 / 64x; x = registered dose of herbicides). The sensitivity of ragweed was determined by visual assessment of damage, 7, 14, 21 and 28 days after treatment (DAT) and reduction of dry above ground mass (28 DAT). The results of the study show that all four investigated herbicides are effective on ragweed, but also that ragweed is differently sensitive to the researched herbicides. Symptoms progressively increased from the first assessment (7 days after treatment-DAT) from the last (28 DAT) for all herbicides investigated. The strongest phytotoxic symptoms was found with in the herbicide foramsulfuron (94% - 28 DNT), and the smallest with imazamox (78% - 28 DNT) at registered herbicide dosages. Dose-response curves were used to estimate dosing for reduction 90% of fresh above ground ragweed mass (ED90): foramsulfuron = 10.11 g ha-1, thifensulfuron = 5,34 g ha-1, imazamox = 102.4 g ha-1. The obtained data indicate that ragweed showed different sensitivity depending of the active substance of the ALS herbicide, so the herbicides were ranked according to the estimated dose required to reduce 50 or 90% of the above ground ragweed mass (from better to worse): prosulfuron<foramsulfuron<tifensulfuron